Essential amino acids differ from non-essential amino acids because essential amino acids cannot be made by the body, but instead, you must get them from your diet (your eating habits). On the other hand, non-essential amino acids are created by the body. You need both amino acids in order for the body to build the wide variety of proteins it needs to survive.
when the grade that you already have were to be put on your report card it would be rounded to the nearest whole number, that being a 70%. so really any grade would help.